Megapixels and resolution – Some thoughts

If you hold a digital camera in public, the first question you will be asked is “How many megapixels ?” If the camera is a professional looking one, the average people will be disturbed by the fact that this information is not displayed prominently in bold letters on the camera.

How much resolution do you really need ?

Megapixels – “the essence” of digital photography – NOT

In the beginning of the new digital photography era, the most difficult problem faced by the manufacturers was building the digital sensors. This is the reason why the number of (mega)pixels on the sensor was of utmost importance.

Later, they noticed that the public received very well this way of describing the “quality” of a digital camera and now, most of the marketing is centered around this figure to the extent of most consumer digital cameras proudly displaying the number of megapixels in easy to see places.

Actually, the number of megapixels alone do not offer a reliable measure of the quality of the camera, less so of the image quality which is greatly influenced by a lot of factors, among them being the sensor size and quality, the lens used, the signal processing and, maybe the most important, the photographer.

Even more, increasing the number of megapixels on the same sensor size is usually less than beneficial for the image quality, because the more crowded the pixels are, the noisier the images will be.

And if you do the math, you will see that increasing the resolution from 4 to 6 Mpx will result in only about 20% increase of the linear image size.

Pixels and pixels

The camera manufacturers are in no hurry to tell us that not all the pixels are created equal so a 6 Mpx image taken with a professional quality camera will have a better quality than an 8 Mpx image taken with a consumer compact camera. The latter will be simply larger.

The major difference in this case will be the captor size, the professional camera pixels being over 4 time larger than those of the consumer compact camera, so much less noise will be recorded.

How many megapixels and resolution do you really need

The answer should be clear after you decide of the final use of the images.

Just for orientation you can use the following guide – a page is a regular magazine page.

Megapixels

Photo Printing

Offset printing

4

A5 – A4
half page – full page

A5
half page

5

A4
full page

A5 – A4
half page – full page

6

A4 – A3
full page – double page

A4
full page

8

A3
double page

A4 – A3
full page – double page

12

over A3
over double page

A3 and over
double page and over

These are very rough guidelines and should be applied to good quality images.

Keep in mind that in digital photography the fewer elements in the image, the easier is to enlarge it without loosing the quality. Best subjects are head and shoulder portraits, products, macro shots. The most difficult subjects for large prints are the detailed landscapes.

Also, getting sharp image from your camera is not simply a matter of how many megapixels and will be discussed at length in another article where you will see that megapixels and resolution are not the same thing.

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